use File::Temp qw(tempdir);
sub sa_t_init {
  my $tname = shift;
  $tname = untaint_var($tname);
...
  unless (-d "log") {
    mkdir ("log", 0755) or die ("Error creating log dir: $!");
  }
  chmod (0755, "log"); # in case already exists with wrong permissions
...
 $workdir = tempdir("$tname.XXXXXX", DIR => "log");

# Simple version of untaint_var for internal use
sub untaint_var {
  local($1);
  $_[0] =~ /^(.*)\z/s;
  return $1;
}